The desulfurization process of waste rubber is to convert waste rubber in elastic state into plastic, viscous and resulfurized rubber after physical and chemical processes such as grinding, heating and mechanical treatment. In the process, S—S and S—C bonds are opened by physical means, chemical means or other means and C—C bonds are not damaged as much as possible; a three-dimensional crosslinked network structure is optionally damaged, but C—C backbone chains are not broken as much as possible; and sulfurized rubber is returned into non-sulfurized rubber.
Currently, the desulfurization of waste rubber at home and abroad mainly adopts two means: the first means is to adopt a dynamic desulfurization device (generally a high-pressure desulfurization tank) for desulfurization and subsequently adopt three or four open mill tabletting devices for post-processing, namely a manufacturing process of one machine and three lines or one machine and four lines is adopted; and the second means is to adopt a spiral continuous desulfurization device for desulfurization and subsequently adopt three or four open mill tabletting devices for post-processing, namely a manufacturing process of new one machine and three lines or new one machine and four lines is adopted.
The first means has the problems of serious pollution, high energy consumption, large labor intensity, instable quality and low efficiency; the high-pressure desulfurization tank has potential safety hazard; and the dynamic desulfurization device and open mills have complex structure, high operation cost and large occupation of land. The second means achieves continuous desulfurization production and has low pollution degree; but as the desulfurization process is spiral free transport process and spiral structures only convey materials forwards in the desulfurization process, S—S and S—C bonds cannot be broken physically; as only thermochemical reaction function is adopted and forced shearing function is not adopted, the desulfurization efficiency is low; the spiral desulfurization device has the defects of large volume, complex structure, difficulty in maintenance, low operation reliability, high operation cost and high energy consumption; the materials are in laminar state in cylinders, are not uniformly heated, and can be easily adhered to blades, so that the quality is instable; and the accumulation of the materials on the blades will also result in explosive problem, and hence the safety performance is low.
The two means adopt three or four open mills for the post-processing of desulfurized rubber, not only have cumbersome processes, large labor intensity and high consumed power but also release a large amount of PM2.5 tail gas in the open mill tabletting process and hence result in air pollution.
The Chinese patent application CN201210422570.0 discloses a device for continuously preparing reclaimed rubber by a two-stage double screw extruder. The device comprises a heterodromous double screw extruder for desulfurization and a homodromous double screw extruder for post-processing. The heterodromous double screw extruder having the advantages of high transport capability and low shearing force is adopted to replace dynamic desulfurization and multispiral desulfurization; the homodromous double screw extruder having the advantage of high shearing force is adopted to replace refining mills by applying high shearing force in low temperature; and finally the reclaimed rubber is obtained by extrusion from heads. In the technology, the heterodromous double screw extruder is adopted for desulfurization; waste rubber is subjected to the engagement of two screws during transport; not only S—S and S—C bonds are broken but also C—C bonds of backbone chains can be easily broken, so that the desulfurized reclaimed rubber has low intensity, and hence the application range and the performance of subsequent reclaimed rubber can be limited; the homodromous double screw extruder is adopted for post-processing and has the defects of complex structure, difficulty in production, high production cost and difficulty in maintenance; and meanwhile, as the materials cannot be easily cooled, an additional cooling means must be arranged to cool the materials from high temperature during desulfurization.
The Chinese patent application CN201310005753.7 discloses a waste rubber desulfurization device and a desulfurization method thereof. A screw with forced shearing function is mounted in a feeding section cylinder and a desulfurizing section cylinder of the device; a two-stage or multistage single-screw desulfurization device is adopted to replace dynamic desulfurization and multispiral desulfurization; and in the desulfurization process, thermochemical and shearing functions are simultaneously applied. Moreover, the device overcomes the defects of difficulty of double screws in controlling the shearing function and complex structure, improves the working stability and reliability, reduces the occupation of land, the energy consumption and the operation cost, and achieves green desulfurization process. The technology adopts the single-screw extruder to achieve the desulfurization of waste rubber, but a matched post-processing device is not provided, so the means of one machine and three lines or new one machine and four lines must be still adopted. The traditional three or four open mills are adopted for the post-processing of the desulfurized rubber, so the defects of the post-processing means still exist.